Front mount blower

[Freud]

I shot these fotos at Bakersfield just for this site.

I was told that Fred Larsen built this application when he worked for Moon. It's like he had on his streamliner.

It is the Potvin application.

FREUD

[panic]

Re: "biggest fab challenge is making a good plenum between the blower and the engine"

I agree - the air speed in those tubes is far too high to turn into the manifold runners. The manifold itself appears to have been designed to minimize height (which was the original purpose), but I can't see the manifold as-is working very well even if the air speed is down by the entry point.
IMHO a better manifold choice with smallest aero penalty is probably a TR with short runners and the entry through the face like some modern EFI.
In addition to larger diameter transfer tubes, they both originate in a box (very crude), and centered on the exhaust side. If the blower drive is reversed the exhaust volume will be from the front 35% or so in the usual triangle, and that should be the minimum area for the tube(s). If you want to use commercial tubing, 2 or 3 each 6" diameter.

[desotoman]

When early front mount blowers were made, most everyone at the time ran all the fuel through the blower. Even with the popoff valve located on the discharge side of the blower, you still had a bomb just waiting to go off. That was probably a good reason to keep the manifold on the small side.

Which brings up a good question. Under pressure do you really need to have good flowing bends in manifolds etc. At first I thought yes, but now I don't know if it is all that important.

A PSI Screw blower is a perfect example. The early Blowers they made compressed air and forced the air out of a delta opening in the back bottom portion of the blower. The compressed air then was trapped (between a plate you had to install on the manifold) and forced to follow built in ribs on the bottom of the blower before being released into the manifold. Yet these blowers took less HP to operate, and delivered cooler air than similar sized 6-71 GMC blowers that discharged directly into the manifold.

Tom G.

[RichFox]

The system may be trash but it sure worked on the Larson and Cummings car

[desotoman]

The system may be trash but it sure worked on the Larson and Cummings car

Rich,

You can't knock success, and they set a lot of records with that car. One of my all time favorite cars.

Tom G.

[panic]

The system may be trash but it sure worked

That statement was also offered in defense of the Ford V8 rather than that weird new Chrysler motor in 1951. Took a few years to be disproved - read Garlits.

[STUTZ]

The only problem with front mounted blowers is that they can't be overdriven. Years ago some guy was selling a coupler to overcome this problem but by then racers found the top mounted blower to be more efficient so he only made a few.

Here's another bitchin' front mount setup.

[RichFox]

The system may be trash but it sure worked

That statement was also offered in defense of the Ford V8 rather than that weird new Chrysler motor in 1951. Took a few years to be disproved - read Garlits.

I worked on a few motors with front mount blowers that seemed to work well at the time. Pratts and Wrights mostly. 2800s and 3350s. I like that Chrysler picture.

[desotoman]

That picture with a centrifugal supercharger reminds me of a time I was at Pomona for the drag races. In the pits I run across Doug Herbert who at the time was running in the Top Alcohol Dragster class. He had a huge centrifugal supercharger mounted in front of the motor. Needless to say NHRA outlawed his setup, but it was cool.

Tom G.

[Glen]

Cagle ran one in the 50s, It was a cabin pressure centrifugal type that was furnished by Don Alderson (Milidon) It was off a DC-7 I believe.

[panic]

they can't be overdriven

...well, not easily.
If you really need the centerlines concentric, a planetary works.
If you can stand some offset (and if moved sideways the blower is still narrower than the engine), a chain drive can be pretty small and cheap. A pair of #50×2 sprockets need only be 2" thick and 8" diameter, moving the blower CL in a 4" circle (4" L or R, up or down, or 2.8" in both directions etc.), locus at the crank . A 20 + 21 set is 1.05 or .952, 21 + 19 is 1.105 or .905, etc.

[desotoman]

I have one that was over-driven. 10% as I recall, been too many years since I looked at it. I bought it off Doug Hartlet (sp) in San Diego. Looked like quick-change gears to me. If it wasn't so buried I would pull it out and take pictures for you to see.

Tom G.

[Milwaukee Midget]

Which brings up a good question. Under pressure do you really need to have good flowing bends in manifolds etc. At first I thought yes, but now I don't know if it is all that important.

Tom G.

Tom, I've thought about that, too.

Part of the question brings up the term "under pressure".  Air at sea level is "under pressure"  - what  you've done by supercharging is changed the relative pressure between the opening, unfilled cylinder and the manifold pressure.  Obstructions in the conduit of flow remain obstructions, regardless of the differential between the open cylinder and the manifold pressure.  Given the short period of time that a valve stays open at, let's say 7500 RPM, any restriction can cost you horsepower.

How much?  There is likely a point of diminishing returns, and I suspect sufficient artificial manifold pressure could overcome a questionable (albeit beautiful) manifold design.

[interested bystander]

Old timers will recall the Burkhart, Burns, Erdman, sometimes Brammer '29 Lakes/ Drag Roadster having a front mount 671 that had gearing capability -maybe with quickchange gears, but don't quote me on that aspect. Things were in a housing as I recall.

[jl222]

That picture with a centrifugal supercharger reminds me of a time I was at Pomona for the drag races. In the pits I run across Doug Herbert who at the time was running in the Top Alcohol Dragster class. He had a huge centrifugal supercharger mounted in front of the motor. Needless to say NHRA outlawed his setup, but it was cool.

Tom G.

  I remember that, the early 90s I think, and was it Walt Austin who built a front drive for a Whipple supercharger on a funny car?
 Thats a setup for somebody [that had room] running a Whipple on gas. Because you could run a large intercooler.
 Bet he still has it 

  JL222